Managing Thrips on Roses with Combinations of Neonicotinoide and Biological Insecticides

The purpose of this research was to develop a bio-intensive pest management system for the thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae), on hybrid roses by incorporating biopesticides [spinosad, emamectin benzoate, and Beauveria bassiana (Balsamo) Vuillemin] with neonicotinoides (imidacloprid and acetamiprid) at half the labeled dose. Soil and spray treatments with these insecticides and their combinations were done at 45-d intervals in 2009 and at 60-d intervals in 2010. An imidacloprid drench was the most effective treatment both years. Spinosad-alone, imidacloprid spinosad, imidacloprid emamectin benzoate, imidacloprid B. bassiana, acetamiprid alone, acetamiprid spinosad, acetamiprid emamectin benzoate, and acetamiprid B. bassiana also gave significant control of thrips at four days after spraying. In 2009, spinosad-alone or in combination with imidacloprid remained effective in controlling thrips populations significantly up to 10 d after insecticide treatment. In 2010, the spinosad-alone treatment gave similar results, but spinosad in combination with imidacloprid (half the labeled dose) showed significant thrips control up to 16 d after insecticide applications.